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Versions: (draft-trammell-ipfix-text-adt) 00 01 02 03 04 05 06 07 08 09 10 RFC 7373

IPFIX Working Group                                          B. Trammell
Internet-Draft                                                ETH Zurich
Intended status: Informational                             June 24, 2014
Expires: December 26, 2014


          Textual Representation of IPFIX Abstract Data Types
                    draft-ietf-ipfix-text-adt-06.txt

Abstract

   This document defines UTF-8 representations for IPFIX abstract data
   types, to support interoperable usage of the IPFIX Information
   Elements with protocols based on textual encodings.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 26, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Identifying Information Elements  . . . . . . . . . . . . . .   3
   4.  Data Type Encodings . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  octetArray  . . . . . . . . . . . . . . . . . . . . . . .   3
     4.2.  unsigned8, unsigned16, unsigned32, and unsigned64 . . . .   4
     4.3.  signed8, signed16, signed32, and signed64 . . . . . . . .   5
     4.4.  float32 and float64 . . . . . . . . . . . . . . . . . . .   6
     4.5.  boolean . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.6.  macAddress  . . . . . . . . . . . . . . . . . . . . . . .   7
     4.7.  string  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.8.  The dateTime ADTs . . . . . . . . . . . . . . . . . . . .   8
     4.9.  ipv4Address . . . . . . . . . . . . . . . . . . . . . . .   8
     4.10. ipv6Address . . . . . . . . . . . . . . . . . . . . . . .   9
     4.11. basicList, subTemplateList, and subTemplateMultiList  . .   9
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  Example  . . . . . . . . . . . . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   The IPFIX Information Model[RFC7012] provides a set of abstract data
   types for the IANA IPFIX Information Element Registry [IANA-IPFIX],
   which contains a rich set of Information Elements for description of
   information about network entities and network traffic data, and
   abstract data types for these Information Elements.  The IPFIX
   Protocol Specification [RFC7011], in turn, defines a big-endian
   binary encoding for these abstract data types suitable for use with
   the IPFIX Protocol.

   However, present and future operations and management protocols and
   applications may use textual encodings, and generic framing and
   structure, as in JSON [RFC7159] or XML.  A definition of canonical
   textual encodings for the IPFIX abstract data types would allow this
   set of Information Elements to be used for such applications, and for
   these applications to interoperate with IPFIX applications at the
   Information Element definition level.

   Note that templating or other mechanisms for data description for
   such applications and protocols are application-specific, and




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   therefore out of scope for this document: only Information Element
   identification and value representation are defined here.

   In most cases where a textual representation will be used, an
   explicit tradeoff is made for human readability or manipulability
   over compactness; this assumption is used in defining standard
   representations of IPFIX ADTs.

2.  Terminology

   Capitalized terms defined in the IPFIX Protocol Specification
   [RFC7011] and the IPFIX Information Model [RFC7012] are used in this
   document as defined in those documents.  In addition, this document
   defines the following terminology for its own use:

   Enclosing Context
      A textual representation of Information Element values is applied
      to use the IPFIX Information Model within some existing textual
      format (e.g.  XML [W3C-XML], JSON [RFC7159]).  This outer format
      is referred to as the Enclosing Context within this document.
      Enclosing Contexts define escaping and quoting rules for
      represented values.

3.  Identifying Information Elements

   The IPFIX Information Element Registry [IANA-IPFIX] defines a set of
   Information Elements numbered by Information Element Identifiers and
   named for human-readability.  These Information Element Identifiers
   are meant for use with the IPFIX protocol, and have little meaning
   when applying the IPFIX Information Element Registry to textual
   representations.

   Instead, applications using textual representations of Information
   Elements use Information Element names to identify them; see
   Appendix A for examples illustrating this principle.

4.  Data Type Encodings

   Each subsection of this section defines a textual encoding for the
   abstract data types defined in [RFC7012].  This section uses ABNF,
   including the Core Rules in Appendix B of [RFC5234], to describe the
   format of textual representations of IPFIX abstract data types.

4.1.  octetArray

   If the Enclosing Context defines a representation for binary objects,
   use that representation.




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   Otherwise, since the goal of textual representation of Information
   Elements is human-readability over compactness, the values of
   Information Elements of the octetArray data type are represented as a
   string of pairs of hexadecimal digits, one pair per byte, in the
   order the bytes would appear on the wire were the octetArray encoded
   directly in IPFIX per [RFC7011].  Whitespace may occur between any
   pair of digits to assist in human readability of the string, but is
   not necessary.  In ABNF:

   hex-octet = 2HEXDIG

   octetarray = 1*(hex-octet [WSP])

4.2.  unsigned8, unsigned16, unsigned32, and unsigned64

   If the Enclosing Context defines a representation for unsigned
   integers, use that representation.

   In the special case that the unsigned Information Element has
   identifier semantics, and refers to a set of codepoints, either in an
   external registry, a sub-registry, or directly in the description of
   the Information Element, then the name or short description for that
   codepoint may be used to improve readability.

   Otherwise, the values of Information Elements of an unsigned integer
   type may be represented either as unprefixed base-10 (decimal)
   strings, as base-16 (hexadecimal) strings prefixed by "0x", or as
   base-2 (binary) strings prefixed by "0b".  In ABNF:

   unsigned = 1*DIGIT / "0x" 1*HEXDIG / "0b" 1*BIT

   Leading zeroes are allowed in any representation, and do not signify
   base-8 (octal) representation.  Binary representation is intended for
   use with Information Elements with flag semantics, but can be used in
   any case.

   The encoded value must be in range for the corresponding abstract
   data type or Information Element.  Out of range values are
   interpreted as clipped to the implicit range for the Information
   Element as defined by the abstract data type, or to the explicit
   range of the Information Element if defined.  Minimum and maximum
   values for abstract data types are shown in Table 1 below.









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           +------------+---------+----------------------------+
           |       type | minimum |                    maximum |
           +------------+---------+----------------------------+
           |  unsigned8 |       0 |                        255 |
           | unsigned16 |       0 |                     65 536 |
           | unsigned32 |       0 |              42 94 967 295 |
           | unsigned64 |       0 | 18 446 744 073 709 551 615 |
           +------------+---------+----------------------------+

             Table 1: Ranges for unsigned abstract data types

4.3.  signed8, signed16, signed32, and signed64

   If the Enclosing Context defines a representation for signed
   integers, use that representation.

   Otherwise, the values of Information Elements of signed integer types
   are represented as optionally-prefixed base-10 (decimal) strings.  In
   ABNF:

   sign = "+" / "-"

   signed = [sign] 1*DIGIT

   If the sign is omitted, it is assumed to be positive.  Leading zeroes
   are allowed, and do not signify base-8 (octal) encoding.  The
   representation "-0" is explicitly allowed, and is equal to zero.

   The encoded value must be in range for the corresponding abstract
   data type or Information Element.  Out of range values are
   interpreted as clipped to the implicit range for the Information
   Element as defined by the abstract data type, or to the explicit
   range of the Information Element if defined.  Minimum and maximum
   values for abstract data types are shown in Table 2 below.

   +----------+---------------------------+----------------------------+
   |     type |                   minimum |                    maximum |
   +----------+---------------------------+----------------------------+
   |  signed8 |                      -128 |                       +127 |
   | signed16 |                   -32 768 |                    +32 767 |
   | signed32 |            -2 147 483 648 |             +2 147 483 647 |
   | signed64 |    -9 223 372 036 854 775 | +9 223 372 036 854 775 807 |
   |          |                       808 |                            |
   +----------+---------------------------+----------------------------+

              Table 2: Ranges for signed abstract data types





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4.4.  float32 and float64

   If the Enclosing Context defines a representation for floating point
   numbers, use that representation.

   Otherwise, the values of Information Elements of float32 or float64
   types are represented as optionally sign-prefixed, optionally base-10
   exponent-suffixed, floating point decimal numbers, as in
   [IEEE.754.2008].  The special strings "NaN", "+inf", and "-inf"
   represent not a number, positive infinity and negative infinity,
   respectively.

   In ABNF:

   sign = "+" / "-"

   exponent = ( "e" / "E" ) [sign] 1*3DIGIT

   right-decimal = "." *DIGIT

   mantissa = 1*DIGIT [right-decimal]

   num = [sign] mantissa [exponent]

   naninf = "NaN" / sign "inf"

   float = num / naninf

   The expressed value is ( mantissa * 10 ^ exponent ).  If the sign is
   omitted, it is assumed to be positive.  If the exponent is omitted,
   it is assumed to be zero.  Leading zeroes may appear in the mantissa
   and/or the exponent.  Values must be within range for [IEEE.754.2008]
   single or double precision numbers; finite values outside the
   approprate range are clamped to be within the range.  Note that no
   more than three digits are required or allowed for exponents in this
   encoding due to these ranges.

   Note that, since this representation is meant for human readability,
   writers may sacrifice precision to use a more human-readable
   representation of a given value, at the expense of the ability to
   recover the exact bit pattern at the reader.  This makes exact
   comparability for equality of floating point values represented using
   these encodings impossible.








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4.5.  boolean

   If the Enclosing Context defines a representation for boolean values,
   use that representation.

   Otherwise, a true boolean value is represented by the literal string
   "true", and a false boolean value with the literal string "false".
   In ABNF:

   boolean-true = "true"

   boolean-false = "false"

   boolean = boolean-true / boolean-false

4.6.  macAddress

   MAC addresses are represented as IEEE 802 MAC-48 addresses,
   hexadecimal bytes, most significant byte first, separated by colons.
   In ABNF:

   hex-octet = 2HEXDIG

   macaddress = hex-octet 5( ":" hex-octet )

4.7.  string

   As Information Elements of the string type are simply Unicode strings
   (encoded as UTF-8 when appearing in Data Sets in IPFIX Messages
   [RFC7011]), they are represented directly, using the Unicode encoding
   rules and quoting and escaping rules of the Enclosing Context.

   If the Enclosing Context cannot natively represent Unicode
   characters, the escaping facility provided by the Enclosing Context
   must be used for non- representable characters.  Additionally,
   strings containing characters reserved in the Enclosing Context (e.g.
   control characters, markup characters, quotes) must be escaped or
   quoted according to the rules of the Enclosing Context.

   It is presumed that the Enclosing Context has sufficient restrictions
   on the use of Unicode to prevent the unsafe use of non-printing and
   control characters.  As there is no accepted solution for the
   processing and safe display of mixed-direction strings, mixed-
   direction strings should be avoided using this encoding.  Note also
   that, since this draft presents no additional requirements for the
   normalization of Unicode strings, care must be taken when comparing
   strings using this encoding; direct byte-pattern comparisons are not
   sufficient for determining whether two strings are equivalent.  See



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   [RFC6885] and [I-D.ietf-precis-framework] for more on the dangers of
   Unicode strings..

4.8.  The dateTime ADTs

   Timestamp abstract data types are represented generally as in
   [RFC3339], with two important differences.  First, all IPFIX
   timestamps are expressed in terms of UTC, so textual representations
   of these Information Elements are explicitly in UTC as well.  Time
   zone offsets are therefore not required or supported.  Second, there
   are four timestamp abstract data types, separated by the precision
   which they can express.  Fractional seconds are omitted in
   dateTimeSeconds, expressed in milliseconds in dateTimeMilliseconds,
   and so on.

   In ABNF, taken from [RFC3339] and modified:

   date-fullyear   = 4DIGIT
   date-month      = 2DIGIT  ; 01-12
   date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31
   time-hour       = 2DIGIT  ; 00-23
   time-minute     = 2DIGIT  ; 00-59
   time-second     = 2DIGIT  ; 00-58, 00-59, 00-60
   time-msec       = "." 3DIGIT
   time-usec       = "." 6DIGIT
   time-nsec       = "." 9DIGIT
   full-date       = date-fullyear "-" date-month "-" date-mday
   partial-time    = time-hour ":" time-minute ":" time-second

   datetimeseconds      = full-date "T" partial-time
   datetimemilliseconds = full-date "T" partial-time "." time-msec
   datetimemicroseconds = full-date "T" partial-time "." time-usec
   datetimenanoseconds  = full-date "T" partial-time "." time-nsec

4.9.  ipv4Address

   IP version 4 addresses are represented in dotted-quad format, most-
   significant-byte first, as it would in a Uniform Resource Identifier
   [RFC3986]; the ABNF for an IPv4 address is taken from [RFC3986] and
   reproduced below:

   dec-octet   = DIGIT                 ; 0-9
               / %x31-39 DIGIT         ; 10-99
               / "1" 2DIGIT            ; 100-199
               / "2" %x30-34 DIGIT     ; 200-249
               / "25" %x30-35          ; 250-255

   ipv4address = dec-octet 3( "." dec-octet )



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4.10.  ipv6Address

   IP version 6 addresses are represented as in section 2.2 of
   [RFC4291], as updated by section 4 of [RFC5952].  The ABNF for an
   IPv6 address is taken from [RFC3986] and reproduced below, using the
   ipv4address production from the previous section:

   ls32        = ( h16 ":" h16 ) / ipv4address
               ; least-significant 32 bits of address
   h16         = 1*4HEXDIG
               ; 16 bits of address represented in hexadecimal
               ; zeroes to suppressed as in RFC 5952

   ipv6address =                            6( h16 ":" ) ls32
               /                       "::" 5( h16 ":" ) ls32
               / [               h16 ] "::" 4( h16 ":" ) ls32
               / [     h16 ":"   h16 ] "::" 3( h16 ":" ) ls32
               / [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
               / [ *3( h16 ":" ) h16 ] "::"    h16 ":"   ls32
               / [ *4( h16 ":" ) h16 ] "::"              ls32
               / [ *5( h16 ":" ) h16 ] "::"              h16
               / [ *6( h16 ":" ) h16 ] "::"

4.11.  basicList, subTemplateList, and subTemplateMultiList

   These abstract data types, defined for IPFIX Structured Data
   [RFC6313], do not represent actual data types; they are instead
   designed to provide a mechanism by which complex structure can be
   represented in IPFIX below the template level.  It is assumed that
   protocols using textual Information Element representation will
   provide their own structure.  Therefore, Information Elements of
   these Data Types are not useful in textual representations.

5.  Security Considerations

   The security considerations for the IPFIX Protocol [RFC7011] apply;
   this document presents no additional security considerations.
   Implementations of decoders of Information Element values using these
   representations must take care to correctly handle invalid input, but
   the encodings presented here are not special in that respect.

   The encodings for all Abstract Data Types other than 'string' are
   defined in such a way as to be representable in the US-ASCII
   character set, and therefore should be unproblematic for all
   Enclosing Contexts.  However, the 'string' Abstract Data Type may be
   vulnerable to problems with ill-formed UTF-8 strings as discussed in
   section 6.1.6 of [RFC7011]; see [UTF8-EXPLOIT] for background.




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6.  IANA Considerations

   This document has no considerations for IANA.

7.  Acknowledgments

   Thanks to Paul Aitken, Benoit Claise, Andrew Feren, and Juergen
   Quittek for the review and comments.  Thanks to Dave Thaler and
   Stephan Neuhaus for discussions which improved the floating-point
   representation section.  This work is materially supported by the
   European Union Seventh Framework Programme under grant agreement
   318627 mPlane.

8.  References

8.1.  Normative References

   [RFC3339]  Klyne, G., Ed. and C. Newman, "Date and Time on the
              Internet: Timestamps", RFC 3339, July 2002.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66, RFC
              3986, January 2005.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC5952]  Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
              Address Text Representation", RFC 5952, August 2010.

   [RFC7011]  Claise, B., Trammell, B., and P. Aitken, "Specification of
              the IP Flow Information Export (IPFIX) Protocol for the
              Exchange of Flow Information", STD 77, RFC 7011, September
              2013.

8.2.  Informative References

   [RFC7159]  Bray, T., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, March 2014.

   [RFC6313]  Claise, B., Dhandapani, G., Aitken, P., and S. Yates,
              "Export of Structured Data in IP Flow Information Export
              (IPFIX)", RFC 6313, July 2011.





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   [RFC6885]  Blanchet, M. and A. Sullivan, "Stringprep Revision and
              Problem Statement for the Preparation and Comparison of
              Internationalized Strings (PRECIS)", RFC 6885, March 2013.

   [RFC7012]  Claise, B. and B. Trammell, "Information Model for IP Flow
              Information Export (IPFIX)", RFC 7012, September 2013.

   [RFC7013]  Trammell, B. and B. Claise, "Guidelines for Authors and
              Reviewers of IP Flow Information Export (IPFIX)
              Information Elements", BCP 184, RFC 7013, September 2013.

   [I-D.ietf-precis-framework]
              Saint-Andre, P. and M. Blanchet, "PRECIS Framework:
              Preparation and Comparison of Internationalized Strings in
              Application Protocols", draft-ietf-precis-framework-17
              (work in progress), May 2014.

   [W3C-XML]  Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and
              F. Yergeau, "W3C Recommendation: Extensible Markup
              Language (XML) 1.0 (Fifth Edition)", September 2008.

   [IEEE.754.2008]
              Instute of Electrical and Electronic Engineers, ,
              "Standard for Floating-Point Arithmetic (IEEE Standard
              754)", August 2008.

   [IANA-IPFIX]
              Internet Assigned Numbers Authority, , "IP Flow
              Information Export Information Elements
              (http://www.iana.org/assignments/ipfix/ipfix.xml)",
              November 2012.

   [UTF8-EXPLOIT]
              Davis, M. and M. Suignard, "Unicode Technical Report #36:
              Unicode Security Considerations", July 2012.

Appendix A.  Example

   In this section, we examine an IPFIX Template and a Data Record
   defined by that Template, and show how that Data Record would be
   represented in JSON according to the specification in this document.
   Note that this is specifically NOT a recommendation for a particular
   representation, merely an illustration of the encodings in this
   document; the quoting and formatting in the example are JSON-
   specific.

   Figure 1 shows a Template in IESpec format as defined in section 10.1
   of [RFC7013]; a corresponding JSON Object representing a record



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   defined by this template in the text format specified in this
   document is shown in Figure 2.

         flowStartMilliseconds(152)<dateTimeMilliseconds>[8]
         flowEndMilliseconds(153)<dateTimeMilliseconds>[8]
         octetDeltaCount(1)<unsigned64>[4]
         packetDeltaCount(2)<unsigned64>[4]
         sourceIPv6Address(27)<ipv4Address>[4]{key}
         destinationIPv6Address(28)<ipv4Address>[4]{key}
         sourceTransportPort(7)<unsigned16>[2]{key}
         destinationTransportPort(11)<unsigned16>[2]{key}
         protocolIdentifier(4)<unsigned8>[1]{key}
         tcpControlBits(6)<unsigned8>[1]
         flowEndReason(136)<unsigned8>[1]

              Figure 1: Sample flow template in IESpec format

           {
               "flowStartMilliseconds": "2012-11-05T18:31:01.135",
               "flowEndMilliseconds": "2012-11-05T18:31:02.880",
               "octetDeltaCount": 195383,
               "packetDeltaCount": 88,
               "sourceIPv6Address": "2001:db8:c:1337::2",
               "destinationIPv6Address": "2001:db8:c:1337::3",
               "sourceTransportPort": 80,
               "destinationTransportPort": 32991,
               "protocolIdentifier": "tcp",
               "tcpControlBits": 19,
               "flowEndReason": 3
           }

               Figure 2: JSON object containing sample flow

Author's Address

   Brian Trammell
   Swiss Federal Institute of Technology Zurich
   Gloriastrasse 35
   8092 Zurich
   Switzerland

   Phone: +41 44 632 70 13
   Email: ietf@trammell.ch








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